- Garage door opener with a light that automatically turns on when the door opens
- Cheap laser pointer
- Voltmeter / multimeter
- Soldering iron & solder
- Needle nose pliers
- Wire cutters and strippers
- Rotary tool (Dremel, etc.)
- Small zip ties
- Sacrificial AC adapter (wall wart)
- Heat shrink tubing
- Light bulb socket outlet adapter
- "Short" light bulbs
One small side note here: LASER is actually an acronym, standing for "Light Amplification by Stimulated Emission of Radiation." I will not be spelling it using all caps in this Instructable, however.
Step 1: Determining the Operating Voltage and Polarity
Remove the laser's battery cover - usually just a screw-on back. Before removing the button cell batteries, take a look at how they are oriented. Button cell batteries typically have their positive terminal on the flat side with all of the writing, leaving the other side with the negative terminal. The writing on the flat side should have a plus or a minus indicating this. If the flat (positive) side is facing the rear of the laser, that means the chassis acts at the positive contact. There should be a spring or something similar acting as the negative contact on the back of the laser's circuit board underneath the batteries.
Take the button cell batteries out, count them, and multiply that number times 1.5 (button cell batteries are typically 1.5V each.) The resulting number is the total voltage needed for your laser to work. For example, if your laser pointer uses two button cell batteries, it will require ~3V to operate.